Conference Presentations

The recent development of a field deployable water isotope analyzer using CRDS technology was used to directly measure the vapor isotopes in real time and at multiple heights above the crop canopy. This technique was coupled with additional samples gathered using conventional techniques and a new xylem water extracting apparatus developed by the IAEA.

Describes a field campaign wherein a Picarro water isotope analyzer was used to measure isotopes in water vapor over a corn field in China for the purpose of studying evapotranspiration. The Picarro sampled vapor along with a cold trap sampling system and the real-time Picarro data was compared to offline analysis of the trapped vapor.

The world’s first continuous flow isotopic TIC/DOC-CRDS measurements are reported here with remarkable achieved precisions. A measurement precision of the isotopic ratio in the range of 0.2 ‰ to 0.4 ‰ was achieved in minutes of measurement time. Such precision readily distinguishes the isotopic DIC and DOC signatures from a set of three different streamwater samples collected from various sites in Northern California. The current TIC/DOC-CRDS setup will enable shipboard measurement and presents a rugged, portable and inexpensive analytical instrumentation alternative to the traditional use of methods based on the more complex and lab-confined isotope ratio mass spectrometry technique.

International Symposium on Isotopes in Hydrology, Marine Ecosystems, and Climate Change Studies:

Hydrothermal fluids from two vent sites along the East Scotia Ridge, E2 and E9, were analyzed for their hydrogen and oxygen isotopic values using a Picarro L1115-i CRDS. The fluids display varying salinity, sulfate and hydrogen sulfide content. None of the samples analyzed in this work showed any signs of spectroscopic interference. Isotopic values of the fluids were combined with salinity, magnesium and silica measurements to determine the possible role of magmatic inputs and phase separation. Oxygen isotope values (reported relative to VSMOW) range from -0.2 to +1.4 ‰ and hydrogen values range from -1.8 to +2.1 ‰. Oxygen isotope values of black smokers at each site differ on average by ~0.4 ‰. Relatively higher 18O values at E2 indicate water-rock reactions may be more prevalent here than at E9. Low salinity and D enrichment at E9 could indicate phase separation. Overall the data suggest that final fluid compositions reflect several complex processes during hydrothermal alteration.

Cavity Ring-Down spectroscopy is becoming a gold standard for atmospheric monitoring. High sensitivity and precision coupled with low drift characteristics ensure optimal operation even in remote field stations or on aircraft and ships. However, current platforms have been limited to two or three species simultaneous observation. Research and development at Picarro have been focused on incorporating the fast optical switching and other technologies required to enable four or more species without compromising the precision and drift that make these instruments valuable to atmospheric scientists. In addition to carbon dioxide and methane, carbon monoxide is widely recognized as an important tracer gas for characterizing anthropogenic emissions. The ability to take inventory of these three critical gases and quantify their sources and sinks is essential for understanding atmospheric change. We have developed a field-deployable analyzer which can measure all three greenhouse gases plus water simultaneously in a single device, while maintaining high levels of precision. The novel 4-species analyzer is able to measure carbon dioxide (CO2) concentration to a precision (5 second, one sigma) of 150 parts-per-billion (ppb), methane (CH4) concentration to a precision of 1 ppb, and carbon monoxide (CO) to a precision of 30 ppb. Analyzer performance is guaranteed over a wide concentration range to allow precise atmospheric characterization in both well-mixed and urban environments. The ability to measure all four species simultaneously in a single instrument with automatic water correction simplifies data collection and enables precise measurements of the dynamic interplay of anthropogenic and biogenic emissions. The added ability to use the instrument for making measurements in the field, in labs, on manned & unmanned vehicles, including planes and ships, and in remote monitoring stations, greatly increases the quantity and quality of the data which can be obtained by a single researcher. Built-in networking capabilities coupled with guaranteed precision and drift specs enable the analyzer to easily integrate into any global network. Current application work using this instrument include: ground-based urban networks, remote atmospheric monitoring, mobile source identification, and flight-based atmospheric cross-sections.

The quantification of fugitive methane emissions from extended sources such as landfills is problematic due to the high temporal variability and spatial heterogeneity of the emission. Additionally, the relationship between the emission rate and the gas concentration at a given location is dependent on the meteorological conditions and local topography, preventing accurate quantification of the emission rate. When the total source emission is of interest, tracer methods allow quantitative measurements to be made using a single, mobile gas analyzer located in the far field of the source (i.e., at a distance that is large compared with the size of the extended source). Making measurements in the far field enables both the extended source and the tracer to be approximated as point sources. By releasing a tracer gas at a known rate at or near the center of the extended area source, the far-field measurement of the ratio of concentrations yields the ratio of emission rates, since the effects of atmospheric dispersion are the same for both species. An ultra-sensitive, dual species gas analyzer based on cavity ring-down spectroscopy has been developed to measure the concentrations of methane and acetylene with the required sensitivity and speed. Acetylene has been selected as a tracer gas due to its low concentration in the environment and the high detection sensitivity that can be achieved. We present field measurements of landfill methane plumes and overlapped acetylene plumes using this new instrument. Both mobile and fixed-point field data obtained with this analyzer are presented that demonstrate simplicity and robustness of the method. Both the strengths and the limitations of the acetylene tracer-based method are discussed.

The regulation of Earth’s climate and its ability to sustain life are critically linked to water as it exists in all three of its phases (gas, liquid, and solid). Earth’s water cycle, its movement between the hydrosphere, biosphere, and the atmosphere, and how it undergoes phase changes, is incredibly complex. While we continue to gain insight into the water cycle, there remains considerable uncertainty in predicting the impacts of future climate change on fresh water supplies and the welfare of life on our planet. This uncertainty exists, in large part, because of a scarcity of highly-resolved spatial and temporal observations of Earth’s hydrology. One proven tool for observing the dynamics of the water cycle is stable isotope analysis of water. Differences in the thermodynamic properties of the isotopologues of water lead to differences in the isotope ratios (18O/16O and D/H) in different environmental water reservoirs. The differences in isotope ratios, in conjunction with meteorological observations, can be used to trace water as it is cycled, and to characterize and identify condensed water sources. Recent advances in cavity ring-down spectroscopy (CRDS) have led to field-deployable instrumentation capable of making real-time high-throughput stable isotope measurements of water. Furthermore, the high precision of such instrumentation (typically < 0.2 ‰ for D and < 0.07 ‰ for 18O) allows for high-resolution measurements that enhance our understanding of the processes that govern natural variability in water isotopes. This presentation demonstrates the results from two different applications of the Picarro isotopic water analyzer. First, the analyzer was used to measure vertical gradients in ambient water vapor isotopes at Blue Oak Ranch Reserve, CA. The Picarro analyzer was deployed with Picarro’s new Standards Delivery Module, a novel, field-durable and automated calibration system that introduces liquid water standards, as vapor, without fractionation effects. The results show clear gradients in water vapor isotopes during cooler nighttime periods, which subsequently break-up during daytime warming. The second set of results show measurements of liquid water samples collected from three different watersheds at Mammoth Lakes, CA. The data are comprised of samples collected from thirty different locations including snow melt lakes, creeks and rain water. The isotopic measurements shed some light on the dominating hydrological phenomena which affect the isotopic content of the water. However, and more importantly, the data demonstrate a complex relationship between the hydrological cycle, volcanic activity and hot springs contributions, and illuminates the fact that a simple explanation involving fractionation along water courses is not sufficient.

While stable isotope techniques have been previously applied to partition evapotranspiration (ET) fluxes in crops, it has only recently become possible to take in situ, long-term, continuous (every 10 seconds) measurements of stable water vapor isotopologues. A Picarro water vapor isotope analyzer (L1115-i) based on cavity ringdown spectroscopy (CRDS) was recently deployed at China’s National Experimental Station for Precision Agriculture during the FAO/IAEA 2nd Research Coordination Meeting on “Managing Irrigation Water to Enhance Crop Productivity under Water-Limiting Conditions using Nuclear Techniques.” Measurements were conducted continuously over several days, sampling from five different heights within and above the canopy of a corn (Zeamays) ecosystem. The continuous measurements by the Picarro analyzer were complimented by additional measurements from the same sampling points, wherein the vapor was cryogenically trapped for later laboratory quantification of the water isotopologues. Stable isotope measurements were taken concurrently with conventional ET flux measurements. The isotope analyses can allow the partitioning of ET into its components: soil evaporation and leaf transpiration. Once daily, during the vapor measurements, liquid water isotope standards were measured by the Picarro analyzer using its included autosampler and subsequently used to calibrate the vapor-phase data. Described here are the analyzer and sampling system as well field data and comparison of the vapor-phase results with the off-line liquid analysis of the cryogenically-trapped vapor.

Picarro has developed an isotope analyzer for lab and field measurements of carbon isotopes in CO2 with the goal of allowing turnkey analysis to be done without the need for flask samples and complex IRMS methods. Here we present a description of the analyzer and its technology as well as recent results from two different collaborators who utilized the analyzer.

Results presented from field trials at Woods Hole Oceanographic Institute and laboratory tests at INSTAAR of a newly available analyzer capable of performing continuous measurements of stable isotopes (δD and δ18O) of liquid water and / or water vapor samples.

Description of field-deployable instrumentation that measures carbon dioxide, methane, and water vapor with both high-accuracy and high-precision would reduce the uncertainty in the determination of terrestrial sources and sinks of these dominant greenhouse gases.

Picarro has developed a field-deployable, real time, ambient gas monitor capable of measuring atmospheric levels of carbon dioxide, methane, hydrogen sulfide, and ammonia with parts-per-billion (ppbv) sensitivity and water vapor with parts-per-million (ppmv) sensitivity. Results from field trials of three different CO2 analyzers at Harvard, Penn State, and the NOAA facility in Boulder CO are shown.

Describes development of and results obtained from an analyzer engineered by Picarro for measuring six important atmospheric contaminants (hydrogen sulfide, ammonia, nitrous oxide, carbon dioxide, water vapor and methane) that are of interest to researchers monitoring Concentrated Animal Feeding Operations (CAFOs).